282 



C. M. CHILD. 



climbed two feet or more up the vertical side. Cilia afford of 

 course the motive power and the slime secreted serves as a 

 means of adhesion to surfaces. Observation of creeping pieces 

 shows clearly that the body is subjected to more or less tension 

 in the longitudinal direction during this movement. Probably 

 the slime secreted by the ectoderm is responsible for most of this 

 tension. I think it possible that this tension may bring about 

 some degree of elongation in much the same way as in Stenostoma 



(Child, '02, '0 3 ). 



In Ccrianthus the tension is due rather to the slime secreted 

 than to the use of the end as an organ of attachment, as is the 

 case in Stenostoma, but the result, viz., longitudinal tension upon 

 the tissues, is similar in both cases. If the tissues here are af- 



20 



\J 



21 



I 



I 



fected by the tension as they are in the turbellaria, elongation 

 must result, whether from growth or from mechanical rearrange- 

 ment of the tissues or cell-elements. 



Soon after beginning my experiments I found that collapsed 

 specimens and pieces in early stages of regeneration crept about 

 very little. It was found that such pieces could be kept without 

 danger of loss in Stender dishes with sides 7-8 cm. in height, 

 which were placed on the bottom of large tanks filled with water ; 

 the pieces never crept out. Later, however, the same pieces 

 would creep out of battery jars with sides 3040 cm. or more in 

 height. In these respects I noted a difference between those 

 pieces which still retained the original oral end and tentacles and 

 those in which oral structures were in process of regeneration. 

 Pieces of the first sort began to creep about soon after closure of 

 the aboral end and distension occurred, /. c., within a few days in 

 many cases, while the pieces with regenerating oral ends usually 



